在 JAVA servlet 中下载 Excel 给出错误文件不匹配

Question

/**
 * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
 */
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
    // TODO Auto-generated method stub
    System.out.println("Hi inside download file :");
    response.setContentType("application/vnd.ms-excel");
    PrintWriter out = response.getWriter();
    String filename = "ResetPassword.xlsx";
    InputStream is = null;
    //is = this.getClass().getClassLoader().getResourceAsStream("LoginConfigurations.xlsx");
    //System.out.println("InputStream :"+is);
    String filepath = "E:\\SPACE_OM_01.02\\SPACE-OM_1.0-V01.02\\WebContent\\Data\\";
    response.setContentType("application/octet-stream");
    response.setHeader("Content-Disposition", "attachment; filename=\"" + filename + "\"");

    // use inline if you want to view the content in browser, helpful for
    // pdf file
    response.setHeader("Content-Disposition","inline; filename=\"" +filename + "\"");
    FileInputStream fileInputStream = new FileInputStream(filepath+ filename);
    /*BufferedReader br = new BufferedReader(new InputStreamReader(is));

        int line;
        System.out.println("Buffer Reader length :"+br.read());
        StringBuilder sb = new StringBuilder();
        while ((line = br.read()) != -1) {
            //sb.append(line);
            out.write(line);
        }
        br.close();*/
    int line;
    System.out.println("Buffer Reader length :"+fileInputStream.read());
    //StringBuilder sb = new StringBuilder();
    while ((line = fileInputStream.read()) != -1) {
        //sb.append(line);
        out.write(line);
    }
    fileInputStream.close();
    out.close();
}

/**
 * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
 */
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
    // TODO Auto-generated method stub
    doGet(request, response);
}

我正在尝试使用按钮下载扩展名为 .xlsx 的 Excel 文件，点击下载按钮后，文件正在下载，当我尝试打开该下载文件时，出现错误，例如 Excel 文件无法打开，因为文件格式或文件扩展名无效。请帮助我解决这个问题。预先感谢。

Answer 1

替换此行：

PrintWriter out = response.getWriter();

用这一行：

OutputStream out = response.getOutputStream();

您正在从 InputStream 读取一个字节，并且应该再次将一个字节写入 OutputStream 以复制它。现在您的字节作为字符发送到 PrintWriter，这是错误的。

并删除这一行：

System.out.println("Buffer Reader length :"+fileInputStream.read());

此行从文件中读取第一个字节并将其丢弃，因此下载的文件丢失了第一个字节。

Answer 2

几天前我遇到了同样的问题，在 Maven 依赖项中添加

<nonFilteredFileExtensions>

后解决了，如下所示：

<plugin>
    <artifactId>maven-resources-plugin</artifactId>
    <version>3.3.1</version>
    <configuration>
        <encoding>UTF-8</encoding>
        <nonFilteredFileExtensions>
            <nonFilteredFileExtension>xls</nonFilteredFileExtension>
            <nonFilteredFileExtension>xlsx</nonFilteredFileExtension>
        </nonFilteredFileExtensions>
    </configuration>
</plugin>

这将阻止二进制文件过滤。